chem
S E C T I O N B
Answer at least TWO (2) Questions from this Section
4. (a) (i) What is an ideal gas? (2 marks)
(ii) Write the ideal gas equation and give the units used for each term in the equation when R = 0.0821L-atm/mol-K. (3 marks)
(b) Why was this equation modified and what is the modified form of the equation? (5 marks)
(c) Calculate, using the modified equation, the pressure at which one mole of chlorine gas will occupy 22400 cm3 at 0oC. (For chlorine, a = 6.49 L2-atm/mol and b = 0.0562L/mol.)
(10 marks)
5. (a) The standard potential of Zn2+/Zn electrode is -0.76V, and the standard potential of the cell
Zn(s)│Zn2+(aq)║Cu2+(aq) │Cu(s) is 1.10V. What is the standard potential of the Cu2+/Cu electrode? (2 marks)
(b) What will be the potential if the zinc ion concentration and the copper ion concentration are
0.025M and 0.25M respectively? (5 marks)
(c) Calculate,
(i) the change in the free energy of the reaction occurring in the cell at the concentrations given in (b); (3 marks)
(ii) the equilibrium constant for the reaction. (3 marks)
(d) (i) What are the essential differences between a Voltaic/Galvanic cell and an electrolytic cell? (3 marks)
(ii) How long will it take to deposit all the copper in an electrolytic cell containing
5000 cm3 copper(II) salt solution that is 0.5 molar through which a current of
1.75 amperes is passed? (RAM for Cu = 63.5) (4 marks)
PLEASE TURN TO THE NEXT PAGE
Page
© The University of the West Indies Course Code CHEM 0061 2005/2006/…….
_____________________________________________________________________________________________
DO NOT WRITE OR TYPE ON THE BACK OF THIS SHEET: USE ONE SIDE ONLY
INSTRUCTIONS: Each page must be signed by the Examiners and where applicable, the University Examiner and/or the External Examiner. Where the examination does not require a University Examiner, the form must be signed by the First and Second Examiners. Completed forms should be handed to the Assistant Registrar
Answer at least TWO (2) Questions from this Section
4. (a) (i) What is an ideal gas? (2 marks)
(ii) Write the ideal gas equation and give the units used for each term in the equation when R = 0.0821L-atm/mol-K. (3 marks)
(b) Why was this equation modified and what is the modified form of the equation? (5 marks)
(c) Calculate, using the modified equation, the pressure at which one mole of chlorine gas will occupy 22400 cm3 at 0oC. (For chlorine, a = 6.49 L2-atm/mol and b = 0.0562L/mol.)
(10 marks)
5. (a) The standard potential of Zn2+/Zn electrode is -0.76V, and the standard potential of the cell
Zn(s)│Zn2+(aq)║Cu2+(aq) │Cu(s) is 1.10V. What is the standard potential of the Cu2+/Cu electrode? (2 marks)
(b) What will be the potential if the zinc ion concentration and the copper ion concentration are
0.025M and 0.25M respectively? (5 marks)
(c) Calculate,
(i) the change in the free energy of the reaction occurring in the cell at the concentrations given in (b); (3 marks)
(ii) the equilibrium constant for the reaction. (3 marks)
(d) (i) What are the essential differences between a Voltaic/Galvanic cell and an electrolytic cell? (3 marks)
(ii) How long will it take to deposit all the copper in an electrolytic cell containing
5000 cm3 copper(II) salt solution that is 0.5 molar through which a current of
1.75 amperes is passed? (RAM for Cu = 63.5) (4 marks)
PLEASE TURN TO THE NEXT PAGE
Page
© The University of the West Indies Course Code CHEM 0061 2005/2006/…….
_____________________________________________________________________________________________
DO NOT WRITE OR TYPE ON THE BACK OF THIS SHEET: USE ONE SIDE ONLY
INSTRUCTIONS: Each page must be signed by the Examiners and where applicable, the University Examiner and/or the External Examiner. Where the examination does not require a University Examiner, the form must be signed by the First and Second Examiners. Completed forms should be handed to the Assistant Registrar